brn-180 ?

[Darryle]

One aspect he's over looking is who made the barrel and what quality is it? What twist.

It's a Brownells branded rifle, we know they didn't manufacture it.

Precision begins with the action and barrel, everything else you might say, is window dressing.

 

[Darryle]

Couple of questions for the OP, looking at the disassembly video, how is the barrel installed into the receiver?

Is it threaded into the upper or retained by those two screws?

 

[DSheetz]

Brownells BRN180's have a 1;8 twist according to their advertisement they also say the barrel is a press fit into the upper receiver, the way that AK barrels are fitted to the receiver. The majority of Brownells AR barrels are made by Satern Barrels and nitride coated by Faxon Firearms, but they also have barrels made by Faxon Firearms, Wilson Combat, Storm Lake, Shilen. The Aero Precision M4E1 upper receiver is an interesting design for sure but they state that they aren't compatible with a piston kit, I don't see them offered in a smooth side either or a side charging model.

 

[DSheetz]

Like so many others here I enjoy learning new things from others and by people asking interesting questions without getting rude toward each other that is part of what makes this a good experience to read these posts.

 

[Catbrain]

From what you are saying I would really focus on seating depth and go shorter in 5 thou increments. If you get one end of the sine curve, fliers will result from the barrel changing direction as it vibrates. You are obviously very close. Eliminating one variable at a time methodically is the answer.

Thanks team carnage-----
I am used to bolt guns where i usually am working the seating out longer- not shorter. Perhaps I am not quite on the node yet. The nodes may be pretty far apart on such a thin barrel. do you think .2 grains steps are appropriate ?
I will try .005 steps on seating after I exhaust the node hunt. I will post pics if I can figure out how.

FYI- I tried russian steel case and it shot about 1.5 moa. (didnt expect that) then I had some cheap brass case stuff that shot about 2+ moa-- go figure)

 

[Catbrain]

I have not had it down far enough yet to see how the barrel is attached. Yall are way ahead of me on that----

I tried a Witt SMD on the muzzle and it seemed to cut the group size a little. Could be harmonics as much as the gas venting at the muzzle. But the darned thing does what it is supposed to do. I CAN shoot it without ears if need be. I ended up moving it to my wolf a1 because the ar-180's handguard would not go over it for field stripping. (a bit too fat). Wish they made a skinnier one.... I really like it.

 

[Catbrain]

so I have now removed the 5x prism scope (which I love-BTW) and I installed a 5-25 arken 5. Then I took my last load--- turned the mag up to 25---- and I got a 5 round group that was 1/3 moa. (3/8 inch) I would say-- that all most good enough to stop there. I think having more magnification helped a lot.
I am calling dogs now--- I hear a huge pack of them just down the road in a cow field. A cow was lost out of that field about a month ago. It looked like one of those UFO
things where the eye and lips and butt were missing. But that may have been just the coyotes after the fact. Are those places where they chew on ? or do I need to watch for the black triangle ship ?

 

[DSheetz]

Yes, that's where the scavengers start eating especially the black vultures in your part of the world. The skunk's, possums and other critters start there as it's easy to gain access to the internal organs.

 

[DDB TX]

While fun, blowback style AR rifles are not as popular as their traditional brethren for this reason. The reviews I saw on Brownells site listed a myriad of issues, accuracy among them.

I am well aware of the intricacies and accurizing of the the AR platform.

Good luck with your tinkering

Short stroke piston system. NOT blowback.

 

[Wallie]

I would want to be absolutely sure that your bullets aren't moving slightly in the neck due to inertia or feeding forces. I've ran into this exact scenario, the groups acted the same. The problem ended up being that about 40% of the projectiles were setting forward when chambered at full bolt speed (not gently lowering the BCG into battery by hand).
If you try single feeding and chambering them gently and your fliers disappear you might have the same.

 

[DDB TX]

I would want to be absolutely sure that your bullets aren't moving slightly in the neck due to inertia or feeding forces. I've ran into this exact scenario, the groups acted the same. The problem ended up being that about 40% of the projectiles were setting forward when chambered at full bolt speed (not gently lowering the BCG into battery by hand).
If you try single feeding and chambering them gently and your fliers disappear you might have the same.

Excellent advice, I learned the hard way to always buy the Lee Factory Crimp dies and add them as another step in the reloading. In spite of plentiful advice that the crimping was not required.

Specifically I learned this whilst working up a 300 WSM load, having been assured by various internet reloading heroes that literally no reload needed a crimp.

And then my chronograph gave me a 300 Weatherby velocity for a 300 WSM round, on a hot Texas afternoon, third shot; and I stopped of course; and the 4th round in the mag had been deeply seated by recoil when I measured it later.

Which means, for those who are new to this stuff, that the bullet being stuffed back into the case by recoil, because it was not crimped, meant that the combustion chamber was reduced by that bullet's backwards thrust into that area; meaning that it had a smaller combustion chamber; which meant that it fired a **** ton hotter than planned. To put it in less technical language, it got crazy hot unexpectedly.
So crimp your rounds, please.

 

[Catbrain]

wallie----
I never thought about the bullet going forward..... only back.
I will draw a sharpie line on the bullet at the edge of the case mouth and (fine sharpie) and check a few after chambering but before firing. I am using the lee factory crimp collet die-- and I like it a lot. Hand weigh each load
to +or - 2 or 3 powder granules.
The last group was 5 rounds inside 3/8 @ 100 yds. (at 25x magnification)
No flier-
Have to shoot that load more to say that is a trend and not a statistical artifact

 

[Wallie]

wallie----
I never thought about the bullet going forward..... only back.
I will draw a sharpie line on the bullet at the edge of the case mouth and (fine sharpie) and check a few after chambering but before firing. I am using the lee factory crimp collet die-- and I like it a lot. Hand weigh each load
to +or - 2 or 3 powder granules.
The last group was 5 rounds inside 3/8 @ 100 yds. (at 25x magnification)
No flier-
Have to shoot that load more to say that is a trend and not a statistical artifact

Offsetting the bullet forward wasn't intuitive for me either… but I stumbled on it, and my calipers weren't lying.
I noticed that the first round was always perfect, which was weird, then I tried a group of "first rounds" by just putting one only in the mag, lock bolt back, one round in the mag, repeat. I got up to 8 or 10 rounds in the same ragged hole with no fliers and set out to figure why rounds 2-5 would get fliers, the only difference being… the rifle feeding them instead of me. Loaded two, shot first then extracted second from chamber and measured base to ojive… and the dang thing had grown about .009"!

 

[Wallie]

Excellent advice, I learned the hard way to always buy the Lee Factory Crimp dies and add them as another step in the reloading. In spite of plentiful advice that the crimping was not required.

Specifically I learned this whilst working up a 300 WSM load, having been assured by various internet reloading heroes that literally no reload needed a crimp.

And then my chronograph gave me a 300 Weatherby velocity for a 300 WSM round, on a hot Texas afternoon, third shot; and I stopped of course; and the 4th round in the mag had been deeply seated by recoil when I measured it later.

Which means, for those who are new to this stuff, that the bullet being stuffed back into the case by recoil, because it was not crimped, meant that the combustion chamber was reduced by that bullet's backwards thrust into that area; meaning that it had a smaller combustion chamber; which meant that it fired a **** ton hotter than planned. To put it in less technical language, it got crazy hot unexpectedly.
So crimp your rounds, please.

I look at crimping as expensive insurance. It can save your ***, your 300WSM example is a perfect case.
I call it expensive because it almost always makes your groups bigger than they would be without crimping.
Don't get me wrong, I'd rather make sure my 300WSM doesn't try to hurt me even if it means 3/4" potential instead of the sub 1/4" I usually set as benchmark.

Also crimping can be the perfect bandaid to jumpstart ignition when slightly less than ideally matched components are used (powder burn rate, bullet weight, barrel length, primer brisance etc).

But I know that if I have to use crimp because my projectile isn't staying put, I have to lower the bar on my usual accuracy standards. I have experienced semi auto feeding setting the bullet forward, and recoil pushing the bullet deeper into the case when subjected to recoil in a magazine. Accuracy (and safety!) sucked when the bullet moves, so a crimp was the best option.